Strings like 'super' will return any title or comment that contains *super*.

The PDF number is often in the comments field, but it is best entered in the Remarks box.

ICSD Help : Elements (Close)
This is just a list of some of the elements in the cell. You can follow the element symbol by a number to indicate the total number of atoms of that particular
element. You may want to specify also the "Element Count", the total number of different elements.
The default logic is AND but you can also use explicitly OR and NOT.
New! Element Groups can now be used (see the Notes).

Example Elements search :(Enter the element symbols or choose from the
Periodic Table).

The ANX formula :
Elements with a positive oxidation state are labelled by the first letters of the alphabet (A-M),
elements with a negative oxidation state are labelled by the last letters (X-Z, W, V, U, T, S),
while elements with oxidation state 0 are labelled by the letters N-R.

The ANX formula is only calculated for fully determined structures.

Hydrogen and its isotopes, when they occur in the positive oxidation state, are disregarded.

If an element in the structure occurs in various oxidation states, this is indicated by different letters.

Within a group of letters, the letters are arranged according to increasing indices.

In the case of a defect structure, a partial site occupation is disregarded.

In mixed crystals, atoms in identical positions are labelled by the letter of the most frequent element.

The Structure Type as defined by Prof. R. Allmann (Marburg) depends on the Space Group, Pearson Symbol and Wyckoff Sequence,
all of which can otherwise be searched for seperately in ICSD. In a few cases the c/a ratio is used. Allmann Structure Types
are at present only defined for cubic and tetragonal materials.

Note that including the Structure Type in quotes eg T="AuCu3" will ensure that only "AuCu3" will be found.

ICSD Help : System (Close)
The crystal system is a rough classification of over-all crystal symmetry. Be careful in using it, since the real symmetry of many compounds is often lower than first determined.

ICSD Help : Laue Class (Close)
Be careful in using the Laue Class symmetry, since the real symmetry of many compounds is often lower than first determined.

ICSD Help : Centering (Close)
Space groups can be classed as having a center of symmetry (Centered) or Non-Centered; many non-centered cells are are also Polar.

ICSD Help : Space Group (Close)
You can select a particular space group from the Space Group Table.
Example Space Group :

Although you can give a single number, you should always specify a range of cell dimensions.

The given range should not be too small; dimensions are stored in rather large increments.

ICSD Help : Wyckoff Sequence (Close)
The Wyckoff Sequence is a (partial) list of Wyckoff positions 2a, 4b etc. You cannot search for an exact string.
When combined with the Space Group it is a powerful means of finding similar structures.
If it is used as the only criterium, searching can be long, so combine it with other criteria as below.

Example Wyckoff Sequence :

2e 2a (The symbols 2e and 2a are found in the Wyckoff sequence in any order).

The Wyckoff Symbol is a different classification based on the number of distinct a,b,c etc positions.
eg "e11" means 11 distinct e-positions. You must search on an exact substring of the Wyckoff Symbol, but to this you can add individual Wyckoff positions.

Cu-O=1.5 : the shortest distance between a Cu and O atom does not exceed 1.5A

Cu-O=1.5-1.7 : the shortest distance between a Cu and O atom is between 1.5A and 1.7A

Cu-O=1.5to1.7 : the shortest distance between a Cu and O atom is between 1.5A and 1.7A

Notes :

This means only the shortest distance between the atoms of the specified kind.

The minimal distance specification is interpreted as a range from 0 up to the specified distance.

A range like Cu-O=1.5-1.7 does not find compounds with bonds in that range and also shorter bonds.

For distances that lie within a precisely defined interval the Distance Select criterium is more powerful.

ICSD Help : Distance Select (Close)Warning : "Distance Select" field not used in search yet !

The pairs of atoms between which distance calculations are to be made according to the optional Distance Range and/or Co-ordination number.
If only one atom name is given, all other types of bonded atom are considered. If a list of atom names is given eg Cu,Al then all from this list are considered.
Example Distance Select :

You must use explicit element names, not element-group names such as TRM. Instead use the generic name ALL. Eg search for Elements "TRM N H not C not O" and then Distance Select ALL-N.

The Distance Select operation requires a relatively large amount of computing time, as the whole of the current subset has to be examined. Distance Selection should be accelerated by reducing the number of entries to be calculated using other selection criteria; in particular either the Min. Distance or Distance Range criteria are required as well.

ICSD Help : Distance Range (Close)Warning : "Distance Range" field not used in search yet !

The range of distances to be considered for the Distance Select atom pairs (also required).

The distance range can either be in absolute values (Angstrom units) or relative to the ionic radii IR. In this case, the specification consists of a tolerance factor followed by "*IR". The tolerance factor is >1 or <1 depending on whether maximum or minimum distances are to be selected.

Maximum distance : 1.15*IR means that a distance between an atom A and any other atom X will only be selected if it is less than 1.15*(ionic radius(A)+ionic radius(X)).

Minimum distance : 0.9*IR means that a distance between an atom A and any other atom X will only be selected if it is greater than 0.9*(ionic radius(A)+ionic radius(X)).

Dist.Select should be accelerated by reducing the number of entries to be calculated using other selection criteria, and in particular the Min.Distance criterium.

ICSD Help : Co-ordination (Close)Warning : "Co-ordination" field not used in search yet !

The distances from each origin atom will only be displayed if the number of destination atoms (coordination number) lies within the range n to k where k >= n. If only one number n is given it is assumed that k=n.

In calculating the coordination, only those atoms selected by the required Distance Select and either the Distance Range or Min. Distance criteria are considered.

Note that Distance Select should be accelerated by reducing the number of entries to be calculated using other selection criteria, and in particular the Min. Distance criterium.